I have a warmflow oil fired combi boiler. With both CH and HW on, the HW pump runs constantly even if water is not being drawn. This prevents heat from being circulate through the radiators. If i turn off the HW at the boiler, the CH pump fires up and all is well. What could be going on?
CH pump will not run when HW is on
- Thread starter JAYBEE1
- Start date
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what model is it
only ones i have have a plate
only ones i have have a plate
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I think it is a 70/90 as there is an X stamped on the manufacturers plate in the 70/90 box. It has a heatstore tank. It looks as if it has tandem pumps. There is a light showing which pump is running. The HW pump light is on all the time if both HW and CH are switched on. The HW light does not go out even if there are no taps running. the only way I can get the CH pump to run, is if I turn the HW off on the timer.
Think I have found the problem - a leak on the heat exchanger.
Turn down the DHW stat to off, not the switch, and if the pump stops, then it is the DHW stat faulty. If it still runs, then flow switch must be stuck.( If a leak on the heat exchanger, it must be one hell of a leak to operate the flow switch.
Although there is always the possibility there is a fault in the pcb or the relay. Follow the fault finder with your multimeter.
Chances are the heat store isnt getting up to temperature.
Is the leak from the heat store?
Is the leak from the heat store?
No the leak was from the cold water feed. I have fixed this leak, but the problem still exists. I am about to go out and have a random poke around, before getting someone out.
Matt, I have turned down the DHW stat to off. The pump still runs for the DHW. It all point towards the DHW pump wanting to run all the time. Could this be a faulty thermostat? I don't have a multimeter, so I am stuck on any electrical diagnostics. I guess I admit defeat and call in the engineer!
Could be afaulty stat, but without a tester or multimeter, impossible to prove
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